Paul Turek
speaker
358 appearances
1 recordings
1 series
first heard Jun 2025
last heard Jun 2025
Paul Turek’s voice in public audio — every appearance, attributed to the second.
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There's a whole issue of what's the source of human evolution. It's really sperm. Yeah. Because they're constantly dividing. They're constantly influenced by the environment. And they're throwing off mutations and epigenetic changes. And what's most interesting for me for this talk is that whatever happens in sperm happens to offspring.
That spermatogonial stem cell is actually the first and the bottom of a tube. There's 12 stages of spermatogenesis. That cell is remarkable. It's actually the human male embryonic stem cell. So I have a patent on that cell. Because if you take that cell and you put it in a niche environment like an embryonic stem cell, it'll become embryonic almost like it can become multipotent. It's pluripotent?
Multipotent. We don't know about pluripotent, but you can form tumors and you can form bone, mesoderm, ectoderm, and endoderm. You can do all three layers of the body. with that adult spermatogonial stem cell.
No. I mean, there are stem cells in the bone marrow. There might be stem cells in fat, but none of this, we showed the capability of the cell is magnificent. I think it's the source. Women have eggs and embryonic stem cells. That's the male embryonic stem cell, in my opinion. It hasn't been taken advantage of yet with cell-based therapy, but it is really incredible what this cell can do.
So that starts out and it usually reproduces mitotically. And then in puberty, it'll go down the path of meiosis, which is a couple steps more than meiosis. There's mitosis involved with meiosis, but it's the having and the mixing up of the chromosomes and the newness of the genome introduces mutations and stuff. And most mutations are bad and some are good. You don't really think about that.
But we could have a long talk about genetics versus epigenetics.
So if you look at healthy human sperm for chromosomal content and what's correct and what's incorrect, probably 2% of them are off. They're still being made. They're just off because it doesn't really click the system to negate it. We don't know at what level of chromosomal abnormalities the system will say this is not. This is absolutely defective. Yeah.
But I would say if you look at making of sperm, it's very logarithmic. You're probably looking at one out of four that are being made go through the epididymis, which is the next 10 days, which is a collecting duck after the testicle where it matures, gets epigenetically modified, and you'll see these zones, different epididymosomes and things like that happening.
And there's a lot of post-production modification, not of DNA essentially, but I think there's a filter going on where a lot of the bad aneuploidy comes out because If you look at the chromosome abnormality rate in testicular sperm before it goes through the rest of the system and compared to ejaculate, it's higher. It's two to three-fold higher.
There are some markers of paternal and maternal origin. It depends on where you're going back in mitosis and meiosis. So they can sort of ascribe it in the embryo. In the sperm, you're really going to have to look at the sperm. And if you see a translocation, some characteristic change in sperm, and you see it in the embryo, then you know it's paternal. But not usually.
And 98% of sperm are typically normal. In a guy with infertility, it might be 95%. Here's an example. If you have a patient with Klinefelter syndrome, a male with an extra X chromosome in every cell in their body, or a transgenic model with that feature.
Okay.
That's the MCAT question. Yep, yep. All right. So in these men, if you look at their sperm aneuploidy, right? So every cell in their body and in the mice, in the transgenic mice, all have an extra X chromosome. Only about 10% will have it in the sperm.
That's math, Peter. That's math. Biology is not math, remember? And I had two Kleinfeldt patients yesterday that I operated on, and they're not doing pre-implantation genetic diagnosis of the embryos that they're going to create from their sperm because the chance is not that high. So it goes from, in mice, 0.1% chance of normal men having XXY sperm or an aneuploid sperm, an abnormal sperm, to 1%.
In humans, it goes from 1% or so to 10%. But 90%, that's remarkable. That's amazing. It's remarkable how efficient this is.
Yeah.
We don't know is the answer. Right. And it's interesting that ovaries are inside. So men get in hot baths and they're cooked.
Spermiogenesis is when You go from the round cell stage and you get half the number of chromosomes and then you have to make a tail and then a whole motor assembly. And that is the most profound transformation of a cell in the body. It takes about three weeks to go from that stage. And we're learning now it's a lot of it's vitamin A driven. Three weeks? Of the six or seven to make a sperm.
Then it's complete and non-modal and it's packaged.
And then the tail makes it... 35 micron tail, yeah. So really magnificent engineering feat. It's got microtubules in the middle and there's these links to the tail. It's like a kite and the engine runs it and the tail wags. Remarkable. 300 genes control movement of sperm alone. There's mitochondrial DNA in there, all that stuff.
Showing 21–40 of 358 · page 2 of 18
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